Structure of hexameric DnaB helicase and its complex with a domain of DnaG primase.
Publication Type:Journal Article
Source:Science, Volume 318, Issue 5849, p.459-63 (2007)
Keywords:Binding Sites, Crystallization, Crystallography, X-Ray, Dimerization, DNA Primase, DNA, Bacterial, DnaB Helicases, Endodeoxyribonucleases, Escherichia coli, Escherichia coli Proteins, Exodeoxyribonucleases, Geobacillus stearothermophilus, Image Processing, Computer-Assisted, Models, Molecular, Protein Binding, Protein Structure, Quaternary, Protein Structure, Secondary, Protein Structure, Tertiary
<p>The complex between the DnaB helicase and the DnaG primase unwinds duplex DNA at the eubacterial replication fork and synthesizes the Okazaki RNA primers. The crystal structures of hexameric DnaB and its complex with the helicase binding domain (HBD) of DnaG reveal that within the hexamer the two domains of DnaB pack with strikingly different symmetries to form a distinct two-layered ring structure. Each of three bound HBDs stabilizes the DnaB hexamer in a conformation that may increase its processivity. Three positive, conserved electrostatic patches on the N-terminal domain of DnaB may also serve as a binding site for DNA and thereby guide the DNA to a DnaG active site.</p>